Muffler insert, and systems, methods and apparatus for making

ABSTRACT

Sound-attenuating mufflers and muffler inserts, and systems and uses of such mufflers and muffler inserts. Continuous fiberglass roving is fed to a pneumatic jet head which fluffs the roving and presents the fluffed roving to a delivery wand at the exit end of the jet head. The delivery wand is moved along a predetermined three-dimensional path such that the wand delivery tip travels along a predetermined three-dimensional path inside a mold while-depositing fluffed fiberglass strands into the mold along the predetermined path. A terminal end portion of a liquid resin conduit is mounted to the fiberglass-dispensing wand, as part of the delivery tip, and drip-feeds liquid resin onto the fiberglass as the fiberglass is being deposited in the mold. The undulating, up and down movement of the delivery tip produces a wave-like undulating pattern in the appearance of the rovings in the resulting molded product.

REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application, under 35 U.S.C. 120, ofSer. No. 14/734,445, filed Jun. 9, 2015, the complete disclosure ofwhich is incorporated herein by reference, in its entirety.

BACKGROUND

This invention pertains to mufflers. In general, a muffler has an outershell, generally steel, which encloses a medium which absorbs and/orotherwise attenuates the sound emitted by e.g. an internal combustionengine. An inlet pipe feeds exhaust gases from the engine into themuffler. An exit pipe carries the exhaust gases away from the muffler.

The medium inside the muffler can be as minimal as the air which isinherently contained inside the muffler shell. Namely, the exhaust gasesand/or shock waves pass/expand from the inlet pipe into the bulk of theshell cavity, and then pass from there into the exit pipe.

In other embodiments, the medium includes a multiple-pass path of pipesand/or baffles inside the muffler shell, where such multiple-pass pathcarries the exhaust gases through an elongate journey through themuffler, and where the length of the path, in combination with theinternal pipe configuration, and other acoustic design properties,collectively contribute to sound attenuation inside the muffler.

More commonly, the muffler shell is packed with a fibrous packingmaterial such as fiberglass which may be separately fabricated as an“insert”. The exhaust gases, and/or the shock waves in the exhaustgases, are allowed and/or directed to flow into and/or through thefibrous packing material whereby the fibrous material absorbs/attenuatesa portion of the sound.

This invention pertains, specifically, not only to mufflers in general,but also to muffler inserts, and methods and apparatus for fabricatingmuffler inserts.

In general, the process of reducing the intensity of the sound emittedby an engine, in a fiberglass-packed muffler, relates to the ability todisburse the sound waves into the medium materials so the medium canabsorb and disburse the energy of the sound waves. While fiberglass istypically used as the fibrous packing material medium, other hightemperature materials can be used in place of the fiberglass.

The muffler shell, which is packed with fiberglass, may also be known asa canister. The inlet pipe, leading into the muffler, carries theexhaust gases from the engine into the muffler. The exit pipe, leavingthe muffler, receives the exhaust gases after such gases have passedthrough the sound-attenuating portion of the muffler, and passes thoseexhaust gases to downstream portions of the exhaust system or to ambientair. The exit pipe leaving the muffler may be an extension of the inletpipe which carries the exhaust gases into the muffler. In thealternative, the exhaust gases may traverse one or more additional pipesinside the muffler whereby there may or may not be additionalexhaust-gas carrying pipes and/or baffles inside the muffler shell,depending on the specifications of the particular muffler; and the exitpipe may not be the same pipe as the inlet pipe.

Some or all of the space inside the muffler shell, which is not occupiedby the inlet pipe, the exit pipe, or any other internal structure insidethe canister, is desirably occupied by uniformly packed fiberglass,which fiberglass provides a substantial portion of the sound attenuationproperties of the muffler.

While some mufflers have a plurality of internal metal baffles and/orpipes which direct the exhaust gases in a tortuous path, other mufflers,as is the case in the embodiments illustrated, attenuate the sound inthe exhaust gases as the pipe carrying the exhaust gases makes astraight-line pass through the muffler. The primary means forattenuating the sound in a straight-through muffler, such as in theembodiments illustrated herein, is to surround the inlet pipe, and/oranother pipe inside the muffler, with a pack/insert of fiberglass orother fibrous material. The fiberglass pack/insert is surrounded by theouter shell such that the fiberglass pack/insert is held between theouter shell of the muffler and an exhaust-gas-carrying tube.

In some instances, the fiberglass insert is packaged in a plastic bagsuch that the plastic layer generally protects a worker's hands from theharsh affects of the fiberglass on human skin. When a muffler containingsuch insert is incorporated into an engine exhaust system, and theengine is activated, the heat from the exhaust gases melts and burns offthe plastic bag, and at about 600 degrees F. sustained temperature, thegases also burn off any e.g. phenolic resin/binder in the fiberglasspack, leaving only the fiberglass as the “pack” inside the muffler. Oncethe fiberglass is released from any such binder as the binder andplastic film are burned off, the fiberglass, in general, expands to fillthe space into which the insert was inserted, namely the volumetric,three-dimensional space being occupied by the insert inside the muffler.

Restated, as a fiberglass pack/insert is fabricated, certain transversestresses are imposed on the individual strands of fiberglass. Thosetransverse stresses are at least in part maintained in the insert by thecombination of any cured resin and any surrounding plastic bag. Once thebag and binder are burned off inside the muffler, any residualtransverse stresses on the strands cause the strands to move intransverse restoration directions until otherwise restrained by otherstrands, or by the muffler shell or pipes, or until the residualstresses are sufficiently attenuated that the fibers no longerexperience a net directional force. Thus, when any binder and anyplastic film are burned off, the fiberglass pack, as a whole, expands toa less-stressed condition, and correspondingly better fills theavailable space inside the muffler shell.

The efficiency with which a muffler attenuates sound depends in part onthe uniformity of the density and uniformity of distribution of thefiberglass in the fiberglass pack at steady state operation of themuffler. Uniformity of fiberglass density and distribution alsoinfluences uniformity of temperature distribution inside the muffler aswell as temperature at the muffler shell, thus effecting thermal stressdistribution in the muffler, which influences use life of the muffler.

The extent to which the expanded fiberglass density and distribution areuniform throughout the available space inside the muffler shell dependsin part on the ability of the insert to conform to the available space,and in part on the uniformity of the density and distribution of thefiberglass in the insert as the insert is being assembled into themuffler shell.

The problem addressed by the invention is that of creating areproducible fiberglass insert which resides between anexhaust-gas-carrying tube and the outer muffler shell, starting withcontinuous fiberglass ravings as the raw material from which the insertis made and which provides desirably uniform density and distribution ofthe fiberglass during steady-state operation of the muffler, whileproviding suitable safety to workers who install such inserts in theprocess of assembling mufflers.

Some known processes by which fiberglass-based products are made and/orfilled into muffler shells result in uneven distribution of thefiberglass inside the muffler shell, or distribution which is notreliably repeatable, such that, when the binder and/or plastic burn off,the fiberglass density is not reliably evenly distributed in theoccupied space, which results in hot spots in the muffler, or there isvariation from muffler to muffler, or from one production run to asubsequent production run.

Other known processes by which fiberglass-based products are made and/orfilled into muffler shells include use of powdered binder, which isaccompanied by air quality issues in the workplace where such productsare made.

Thus it is desirable to provide systems, apparatus, and methods ofuniformly distributing fiberglass and a binder in a muffler insert.

More specifically, it is desirable to provide systems, apparatus, andmethods for uniformly distributing such fiberglass while including suchbinder in a mold which receives the fiberglass and binder and whichprovides a shape-constant core for the insert.

It is also desirable to provide systems, apparatus, and methods by whichuniformity of density and distribution of such fiberglass-binder core isreliably reproducible over an extended period of time without airquality issues related to a powdered binder.

It is further desirable to provide systems, apparatus, and methods forfabricating such muffler insert article, and muffler into which theinsert article has been assembled, wherein the quality of the insertproduct is reliably reproducible.

It is yet further desirable to provide systems and apparatus adapted tofabricate a fiberglass-based muffler insert and wherein the insertfabricated using such systems and apparatus defines a generally uniformdistribution of fiberglass throughout the volume defined by such insert,and wherein the insert is reliably reproducible.

It is further desirable to provide a method of fabricating such mufflerinsert article, which method includes using a jet head to fluff acontinuous fiberglass roving and to move a wand extension of the exitend of the jet head about, inside the mold, positively placing thefiberglass-based material in such mold at staged multiple elevationsinside the mold.

It is still further desirable to place a binder, in non-powder form, inthe mold simultaneously with the placement of the fiberglass in themold.

It is still further desirable to mount a binder dispenser exit locus inclose proximity to the exit end of the nozzle of the fiberglassdispenser such that the binder is placed in close proximity to thefiberglass being concurrently placed in the mold.

It is yet further desirable to provide an industrial-level computerwhich guides specific placement of such fiberglass and binder in themold along a predetermined 3-dimensional path.

It is also desirable to design the predetermined three-dimensional pathaccording to the volumetric profile of the mold cavity into which suchfiberglass and binder are to be placed.

SUMMARY

This invention provides sound-attenuating mufflers and muffler inserts,and systems and methods for fabricating such muffler inserts.

In the invention, one or more continuous fiberglass rovings is fed to apneumatic nozzle/jet head which fluffs the rovings and presents thefluffed rovings to a delivery wand at the exit end of the jet head. Adelivery system drive drives the jet head/wand assembly along athree-dimensional path such that the wand delivery tip travels along apredetermined three-dimensional path inside a mold thereby depositingthe continuous, fluffed fiberglass strands in the mold along thepredetermined, and therefore predictable, path. A liquid-adhesive resindispenser is mounted to the fiberglass-dispensing wand, as part of thedelivery tip, and drip-feeds liquid-adhesive resin onto the fiberglassas the fiberglass strands are being deposited/placed in the mold. Theundulating, up and down movement of the delivery tip produces awave-like undulating pattern in the appearance of the rovings in theresulting molded product.

In a first family of embodiments, the invention comprehends a moldedfiberglass-based sound attenuating muffler insert core comprising agenerally shape-constant cured mixture of continuous fiberglass rovingand cured liquid resin binder, the insert core having an outer surfaceconfigured to interface with an inside surface of a muffler shell intowhich the insert core is adapted to be assembled so as to providefiberglass-based sound attenuation in a muffler when the muffler isfully assembled, whereby the muffler insert core is adapted tomaintaining a relatively constant shape configured to interface with theinside surface of the muffler shell, and wherein the continuousfiberglass roving has been fluffed so as to reduce the density of theroving, and wherein the fluffed roving, in elevation view of the insertcore, exhibits a conspicuously wave-like, undulating pattern.

In some embodiments portions of the fluffed roving deviate from thewave-like undulating pattern.

In some embodiments, portions of the fluffed roving randomly deviatefrom the wave-like undulating pattern.

In some embodiments, portions of the fluffed roving exhibit generallyisolated circular patterns.

In some embodiments, the insert core has been fabricated by inserting anexit wand tip of a jet head into an insert core mold, and moving theexit wand tip along an up and down zigzag path while delivering thefluffed fiberglass roving into the mold.

In some embodiments, the invention comprehends a muffler insert madewith a such insert core, and a polymeric film shrunk about the mufflerinsert core.

In some embodiments, the invention comprehends a muffler made with asuch muffler insert.

In a second family of embodiments, the invention comprehends a method ofcharging a cavity in a mold with a combination of a fiberglass and abinder, the method comprising conveying a fiberglass roving from asource to a jet head; fluffing the fiberglass roving in the jet head andurging the fluffed fiberglass roving out an exit end of the jet-head, toa delivery tip; conveying a curable liquid resin from a resin source tothe delivery tip; and inserting the delivery tip into a mold cavity and,in the mold cavity, moving the delivery tip in a combination of up anddown and transverse motions along a delivery path, and simultaneouslydispensing both fluffed fiberglass roving and liquid binder into themold, thereby charging the fluffed fiberglass roving and the liquidresin into the mold cavity.

In some embodiments, the method further comprises dispensing the liquidresin binder drop-wise onto the fluffed fiberglass roving as thefiberglass roving is being dispensed into the mold.

In some embodiments, the method further comprises moving the deliverytip along a zigzag up and down path wherein the delivery tip moves in adiagonal direction which simultaneously includes both a vertical vectorand a horizontal vector.

In some embodiments, the method further comprises, initially in a firststage of charging the mold cavity, confining movement of the deliverytip to a lower first portion of the mold cavity.

In some embodiments, the method further comprises, in a subsequentsecond stage of charging the cavity, confining movement of the deliverytip to a relatively upper second portion of the mold above the firstportion of the mold.

In some embodiments, the invention comprehends a muffler insert,comprising a muffler insert core made according to the methods of theinvention, and a polymeric film shrunk about the muffler insert core.

In some embodiments, the invention comprehends a muffler, comprising amuffler outer shell, and a muffler insert made according to the methodsof the invention.

In a third family of embodiments, the invention comprehends a system forcharging continuous fiberglass and liquid resin into a mold in theprocess of fabricating a muffler insert core, the system comprising acontinuous fiberglass source, supplying a continuous fiberglass roving;a fiberglass feed mechanism adapted to feed the fiberglass roving fromthe fiberglass source; a resin source, supplying a liquid resin througha resin conduit; a resin feed mechanism adapted to feed the liquid resinfrom the resin source, through a resin conduit; a delivery systemassembly comprising a jet head having an entrance and an exit, receivingthe fiberglass roving from the fiberglass source, an exit wand, and adelivery tip wherein an exit end of the exit wand and an exit end of theresin conduit are held together so as to deliver supplies of thefiberglass roving and the resin at a generally common location; a drivesystem adapted to drive the delivery tip along a three-dimensional pathinside the mold for the muffler insert core; and a programmablecontroller adapted to control delivery of the fiberglass roving and theresin into the mold.

In some embodiments, the programmable controller controls the pathtraversed by the delivery tip in the mold.

In some embodiments, the programmable controller controls timing duringwhich fiberglass and resin are delivered into the mold.

In some embodiments, the fiberglass feed mechanism comprises a tractionfeed device having at least first and second feed wheels, and whereinthe fiberglass roving encounters at least one of the feed wheels atleast two times.

In some embodiments, the resin feed mechanism comprises a flow controlvalve.

In some embodiments, the resin source comprises a pressure reservoir.

In some embodiments, the resin feed mechanism comprises at least one ofa servo motor or a stepper motor, to assist in controlling quantity ofresin fed to the mold.

In some embodiments, the exit wand has an outer diameter of about 0.4inch to about 0.75 inch, optionally about 0.5 inch, and an innerdiameter of about 0.32 inch to about 0.65 inch, optionally about 0.42inch.

In some embodiments, the resin conduit is held to the jet head wandproximate the delivery tip by a resiliently expansible sleeve.

In some embodiments, the programmable controller provides activationand/or deactivation signals directed toward at least the traction feeddevice, and the delivery system assembly drive which controls the pathof the delivery tip in the mold.

In some embodiments, the programmable controller controls positioning ofthe mold below the delivery tip.

In some embodiments, the invention comprehends a muffler insert,comprising a muffler insert core made using a system of the invention;and a polymeric film shrunk about such muffler insert core.

In some embodiments, the invention comprehends a muffler, comprising amuffler outer shell; and a muffler insert, made using a system of theinvention, inside the muffler outer shell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial view of a prior art straight-through-flow mufflerwhich includes a muffler insert.

FIG. 2 is a pictorial view of a muffler insert, including an insertcore, and a plastic film surrounding the outer diameter of the core.

FIG. 3 shows a pictorial top view of an exemplary circular-cylindricalmold for a muffler insert core.

FIG. 4 is a pictorial view showing a mold, bearing a prior art moldplug, after the mold has received a charge of a mixture of choppedfiberglass and powdered binder.

FIG. 5 is a side elevation view showing a portion of a prior art processwherein a funnel was used to guide a mixture of powdered binder andchopped fiberglass into an underlying mold such as the mold of FIG. 3.

FIG. 6 shows a top pictorial view of first and second molds useful inthe invention for making muffler cores.

FIG. 7 shows a flow chart of a process of the invention.

FIG. 8 shows a representative pictorial view of an adhesive containerwhich supplies adhesive to the process of the invention, and two spoolsof fiberglass rovings/rope which feed continuous strand bundles offiberglass roving to a feed pipe which leads to a pneumatic texturizingjet head, which jet head fluffs the fiberglass rope and positions thefluffed fiberglass into a mold such as those illustrated in FIG. 6.

FIG. 9 is a side elevation view of the traction feed device and theentrance end of the fluffing nozzle.

FIG. 10 is a side elevation view of a lower portion of the fluffing jethead, including a wand, and a resin-dispensing conduit.

FIG. 11 is a side pictorial view showing a wand extending from the jethead, and the wand extending into the mold and the lower end of the wandat a lower level in the mold, placing fiberglass and resin at such lowerlevel in the mold.

FIG. 12 is a side pictorial view as in FIG. 11, with the jet head raisedsuch that the lower end of the wand is placing fiberglass and binder atan intermediate height in the mold.

FIG. 13 is a side pictorial view as in FIGS. 11 and 12, with the jethead raised further such that the lower end of the wand is placingfiberglass and binder at a relatively upper height in the mold.

FIG. 14 shows first and second insert molds after the molds have beenfilled with a specified quantity of fiberglass and resin, and after moldcaps have been placed over the fiberglass/resin combination, at the topsof the molds.

FIG. 15 is a photo copy of a side elevation view of a substantialportion of a muffler core of the invention after the core has beenenclosed in a shrink film, the photo copy showing the wave-like,undulating pattern in the contained fiber.

The invention is not limited in its application to the details ofconstruction, or in the arrangement of the components, or in thespecific methods set forth in the following description or illustratedin the drawings. The invention is capable of other embodiments or ofbeing practiced or carried out in other various ways. Also, it is to beunderstood that the terminology and phraseology employed herein is forpurpose of description and illustration and should not be regarded aslimiting. Like reference numerals are used to indicate like components.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 shows a cut-away illustration of a typical straight-flow-throughmuffler, generally designated as 10. In muffler 10, a cylindrical insert12, shown generally in FIG. 2, is assembled into a muffler shell 14,thus forming the desired muffler 10 having a contained shrink-wrapped,fiberglass-based insert. Muffler shell 14 includes a lead-in section(not shown), an exit section 16, a relatively enlarged muffling section18, a lead-in transition section (not shown) between the mufflingsection and the lead-in section, and an exit transition section 20between the muffling section and the exit section. In some instances,the portions of the muffler shell represented by the lead-in section andthe lead-in transition section are not assembled to the remainingportions of the muffler shell until after the insert has been assembledinto the muffling section. FIG. 1 thus shows the exit section of themuffler shell, as well as the exit transition section and a portion ofthe muffling section. The lead-in section and the lead-in transitionsection are typically mirror images of the exit section and the exittransition section, respectively.

The outer circumference 22 of the finished, shrink-wrapped, insert 12generally conforms to the inner surface 24 of the muffling section ofthe muffler shell whereby the insert can be inserted into the mufflingsection by sliding the insert longitudinally into the muffling section.

In the embodiment illustrated in FIG. 1, exhaust inlet pipe 26 extendsstraight through the inlet section, through the inlet transitionsection, and through the muffling section of the shell. Inlet pipe 26has apertures 28 which allow exhaust gases to exit the exhaust pipe andmingle with the fiberglass in insert 12, as well as allowing the shockwaves in the exhaust gases to exit pipe 26 through apertures 28 which,in combination, results in the muffler providing a substantialsound-reducing affect.

Inlet pipe 26 can be assembled to the shell after the insert has beenassembled to the shell. In such instance, the inlet pipe is insertedlongitudinally into the insert aperture 30 which faces toward the readerin FIG. 2. As the inlet pipe is inserted into aperture 30, the leadingedge of pipe 26 engages any portion of the shrink film which extendsinto aperture 30, and pushes that film inwardly into the aperture. Asthe film is pushed into the aperture, the film stretches and movestoward the inner surface of the aperture, such that a portion of thefilm may lie between the inner surface of the aperture and the outersurface 32 of pipe 26.

In the alternative, inlet pipe 26 can be first assembled to the lead-insection and lead-in transition sections of the muffler shell. Theso-assembled combination can then be assembled to the remaining portionsof the muffler after the insert is assembled into the shell, includingsliding the inlet pipe longitudinally into the aperture of the insert asdiscussed above. Any remaining joints in the muffler are then closed,thereby providing final closure of the closed muffler product.

An illustrative cylindrical mold 34 which can be used with prior artmethods of making inserts is shown in FIG. 3. Such mold 34 has a top, abottom, and a height “H” between the top and the bottom. An innercylinder wall 36 of the mold is concentric with an outer cylinder wall38. Both cylinder walls 36, 38 are mounted to base plate 40 whichextends across the bottom of the mold and thus closes off the bottom ofthe mold. A cylindrical fiber-receiving cavity 42 extends from thebottom of the mold to the top of the mold, between cylinder walls 36 and38. A central cavity 44, which does not receive fiber, is enclosed byinner cylinder wall 36.

In order to prevent fiber from entering cavity 44 in such prior artprocess, a cone-shaped plug 46, as illustrated in FIG. 4, is placed overcavity 44. An adapter 48, shown in FIG. 5, is then placed over the mold,leaving open the top of fiber-receiving cavity 42. A funnel 50 ismounted to the top of the adapter, and a charge of a fiberglass-bindermixture is dropped through the funnel into mold cavity 42. Multiplecharges of the mixture are dropped into the mold, with the mixture inthe mold being tamped between such chargings.

Turning now to the invention, FIG. 6 shows a top view of first andsecond molds 34 mounted to a common base plate 40. The molds 34 differfrom the mold illustrated in e.g. FIG. 3 in that the radial dimension ofthe mold cavity varies about the perimeter of the mold, and a pluralityof steam release ports 35 extend through the sides of the mold forexhausting flowing air which enters the mold as well as through baseplate 40 at the bottoms of the mold cavities. Accordingly, a processsuch as the prior art process referred to above, which fills the moldcavity with a fiber-binder mixture by “dropping” a charge of the mixtureinto the mold cavity, runs the risk that the insert will have arelatively lower fiber density where the radial dimension of the cavityis relatively larger, and a relatively greater fiber density where theradial dimension of the cavity is relatively smaller.

FIG. 7 shows the mold-filling system 51 and process of the inventiondiagrammatically. Fiberglass roving 52 is drawn from a fiberglasssource, such as one or more spools of roving 54 (FIG. 8) by a tractionfeed device 56. Traction feed device 56 draws the fiberglass rovingthrough a conduit 58 and delivers the roving to a delivery systemassembly 60. FIGS. 9 and 10 show elements of the delivery systemassembly.

Also as illustrated in FIGS. 7 and 8, liquid adhesive resin is drawnfrom a resin source/reservoir 66 by an adhesive resin pump 68; or in thealternative the resin reservoir can be pressurized. The adhesive pump,or pressure from the resin reservoir, delivers the liquid adhesiveresin, through an adhesive conduit 70, to delivery system assembly 60,alongside the fiberglass rovings which arrive through conduit 58. Atleast the terminal portion of resin conduit 70, proximate deliverysystem assembly 60, is flexible such that the conduit can toleratesubstantial movement of the terminal portion of the conduit, of at leastabout 6-10 inches, in any direction from a home position.

A suitable adhesive resin is a single stage phenolic resin in water,available from Plastics Engineering Company, Sheboygan, Wis. as Plenco15100 phenolic resin.

Delivery system assembly 60 includes a mounting housing 74, a pneumaticjet head 76 mounted to the mounting housing, and a wand 78 extendingfrom the exit end of the jet head. In the illustrated embodiment, theterminal portion of resin conduit 70 is mounted to wand 78 by alocalized clamping device 80 such as a zip tie. Conduit 70 extends fromlocalized clamping device 80 alongside wand 78 and is held in generalcontact with wand 78 by a radially resiliently expansible sleeve 82. Thecollective effect of clamping device 80 and sleeve 82 is to hold theterminal end portion of the resin conduit generally fixedly attached to,and extending longitudinally alongside, the wand, and wherein theterminal exit end of the resin conduit is proximate the terminal exitend of the wand and, in combination, provides a fiber-resin delivery tip84. The terminal exit ends of wand 78 and conduit 70 terminate atapproximately a common height at the delivery tip.

An optional resin valve 86 may be located anywhere between pump 68 andthe exit end of conduit 70, Resin pump 68 may be a positive displacementpump which can be calibrated to deliver the resin at a desired rate.Resin valve 86 is a second element which further facilitates controllingthe flow of resin and the rate of flow of resin through the resinconduit. Where the resin reservoir 66 is pressurized, valve 86 can belocated anywhere along the length of conduit 70, optionally proximatethe exit end of conduit 70.

In the invention, delivery system assembly 60 overlies a mold 34 andmoves relative to the underlying mold, thus to insert delivery tip 84into the mold, to move the delivery tip about in the mold along apredetermined, and therefore predictable, path. Such movement of thedelivery system assembly, and thus the path along which the delivery tipmoves, is effected by a drive system 88, such as a mechanical drivesystem such as an industrial robot.

The operation of mold-filling system 51 is controlled by a programmablelogic computer (PLC) 90, such industrial robot, or other drive system.PLC 90 is programmed to issue commands to resin pump 68 as to thepumping rate or pressure level in reservoir 66, and to resin valve 86regarding the degree of opening and/or closing of the valve. The resinpump can be a positive-displacement pump whereby the PLC can specify thenumber of pump rotations which provide the desired quantity of resin.PLC 90 can also communicate with drive system 88 regarding the path tobe traversed by the delivery system assembly so as to cause delivery tip84 to traverse the desired path in a mold. PLC 90 may optionally controlthe locating of mold 34 under delivery tip 84 so as to coordinate therelative positioning of the mold relative to the delivery tip. PLC 90also issues commands to traction feed device 56 in order to control thequantity and rate of delivery of fiberglass rovings to the deliverysystem assembly. The traction feed device may be driven by a steppermotor or a servo motor whereby the number or incremental advances of themotor can be used to control the quantity of fiber delivered to the jethead.

With the PLC thus in control of the rate at which resin and fiber arefed to the delivery system assembly, and in control of movement of thedrive system and optionally the location of the mold, the PLC thuscontrols delivery of the fiber and resin into the mold, by the deliverytip, along the predetermined path.

In the alternative, the amount of resin and fiberglass delivered to amold may be calibrated by measuring the quantity of resin and fiberwhich is delivered during a set period of running time. The quantity offiber is adjusted by the PLC adjusting the drive rate at the tractionfeed device. The quantity of resin is adjusted by manually adjusting theflow rate at resin valve 86. Once the feed rates have been calibratedfor both the fiber and the resin for the set period of time, the moldfill cycle is controlled by the PLC controlling the length of timeduring which fiber and resin are being introduced into the mold.

Traction feed device 56 includes a first relatively larger wheel 57 aand a second relatively smaller wheel 57 b, both mounted to housing 74.Fiberglass roving 52 enters traction feed device 56 at wheel 57 a, andpasses about 180 degrees about wheel 57 a, and thence moves to wheel 57b. The roving passes about 270 degrees about wheel 57 b and thencetravels back to wheel 57 a and again traverses about 180 degrees aboutwheel 57 a, including about 90 degrees of traverse on wheel 57 a incommon with the incoming roving. After the second pass about wheel 57 a,the roving travels along a loose loop to the inlet end of texturizingjet head 76.

Jet head 76 is also known in the art as a nozzle. A suitable suchnozzle/jet head can be assembled from a jet cage with cutting device, ajet casing, a jet needle, and a jet venturi, all available from AmericanDietz+Schell, Simpsonville, N.C.

Such jet head assembly includes a pneumatic cylinder which engages thefiber upstream from the exit from the jet head. Such pneumatic cylinderis activated by a discrete output within the PLC program and therebyholds the fiber in place while the mechanical drive system moves thedelivery system assembly to its next point of mold filling so the fiberdoesn't get pulled out of the jet head prematurely. Namely, any time thePLC is not commanding that the delivery tip be in a mold cavity fillingthe mold, the pneumatic cylinder is engaged against the fiber to keepfiber from leaving the jet head.

Referring now to FIGS. 10-13, first and second molds, mounted on acommon base plate 40, are positioned generally under the delivery systemassembly such that the delivery tip is generally above a fiber-receivingcavity in the mold. Such mold may be positioned by the PLC driving aconveyor 92 so as to position the mold under the delivery tip, or may bemanually positioned under the delivery tip. The position of the mold maybe detected by any known sensor, such as a sensor 94, illustrated inFIG. 6. With the mold in position, the PLC commands drive system 88 tobegin moving the delivery system assembly, and thus the delivery tipsuch that the delivery tip descends into the mold and begins movingalong the predetermined path programmed into the computer. At the sametime, the PLC commands the resin pump and the traction feed device tobegin feeding resin and fiber to the delivery system assembly, thus tothe delivery tip at the predetermined rates, as well as to deliver anyprogrammed-in commands to the resin valve. The command connectionsbetween the PLC and the various mold-filling system elements areillustrated by dashed lines 96 in FIG. 7.

As the fiberglass roving passes through jet head 76, the jet headaerates the roving so as to cause a fluffing of the roving such that theroving exits the jet head, and thus the wand, and enters the mold, at asubstantially reduced density relative to the density of the roving onspool 54. Accordingly, the fluffing of the roving means that, as theroving exits wand 78, the density of the roving has been reduced suchthat the overall amount of space occupied by the roving has beenexpanded, whereby the roving is substantially lighter in density thanthe roving on spool 54. As illustrated by the droplets 98 shown in FIG.10, the resin is fed drop-wise from the exit end of conduit 70 atdelivery tip 84 simultaneously with the feeding of the fluffedfiberglass through delivery tip 84. As the fiberglass and resin arebeing fed separately from delivery tip 84, drive system 88 is moving thedelivery system assembly, and thus delivery tip 84, along thepredetermined path inside the mold, whereby fiber and resin are beingdelivered to the mold along the predetermined path. By thus controllingthe delivery path, and the rate of delivery of the fiber and resininside the mold, the density of the fiber-resin combination inside themold can be controlled so as to deliver a relatively consistent densityof fiber and resin to all portions of the mold volume.

The movement of the delivery tip illustrated in FIG. 11 illustrates themovement of the delivery tip during the first phase of delivery of fiberand resin into the mold. In the movement illustrated in FIG. 11, thedelivery tip extends to a location near the bottom of the mold. Up-downarrow 100 indicates that delivery tip 84 moves vertically up and down inthe mold, with such up and down movement being confined to a lowerportion of the mold, such as to the lower ⅓ of the height of the mold.

Curvilinear arrow 102 indicates that, as delivery tip 84 is moving insuch up-down motion, the delivery tip is also moving transversely alonga path defined both horizontally and vertically inside the mold volume,thus about the circumferential outline of the mold cavity between innerand outer walls 36, 38. The actual definition of the transverse portionof the path depends on the profile of the cavity between walls 36, 38.Where the mold cavity is relatively narrow and circular as in the moldillustrated in FIG. 3, the transverse portion of the path travelled bydelivery tip 84 may be generally circular, all the while the deliverytip is travelling an up-down path as the delivery tip circumscribes thecircular portion of the path about the circumference of the mold cavity.

Where the mold cavity has relatively greater dimensions between theinner and outer walls, or where the mold cavity has narrower and broaderpassages about the perimeter of the mold cavity as in FIG. 6, or wheremore than one inner wall 36 extends through the mold cavity, thedelivery tip moves along a transverse portion of the path which, fromtime-to-time, extends with a radial component, as well as acircumferential component, in order to deliver a relatively consistentdensity of fiber and resin to all areas of the lower level of the mold.

The movement of the delivery tip illustrated in FIG. 12 illustrates themovement of the delivery tip during a second phase of delivery of fiberand resin into the mold. The movement illustrated in FIG. 12 iscommenced after completion of the movement contemplated in FIG. 11 inthe lower portion of the mold. In the movement illustrated in FIG. 12,the delivery tip extends to a location near the middle of thetop-to-bottom height of the mold. Up-down arrow 100 again indicates thatdelivery tip 84 moves vertically up and down in the mold. In this secondphase of delivery of fiber and resin into the mold, such up and downmovement is confined to a mid-height portion of the mold, such as to themiddle ⅓ of the height of the mold. The difference in height of thedelivery tip can be seen conceptually by comparing the length of sleeve82 which is visible in FIG. 12 to the length of sleeve 82 which isvisible in FIG. 11. Given that the same sleeve is being used in both ofFIGS. 11 and 12, given that a greater portion of the length of thesleeve is visible in FIG. 12, the delivery tip is at a higher elevationin the mold in FIG. 12 than in FIG. 11.

Again, curvilinear arrow 102 indicates that, as delivery tip 84 ismoving in such up-down motion in this second phase of delivering fiberand resin to the mold, the delivery tip is also moving transverselyabout the horizontally-defined profile of the mold volume, thusthree-dimensional motion about the circumferential outline of the moldcavity between inner and outer walls 36, 38. The actual definition ofthe transverse component of the path depends on the profile of thecavity between walls 36, 38. Where the mold cavity is relatively narrowand circular as in the mold illustrated in FIG. 3, the transversecomponent of the path travelled by delivery tip 84 may be generallycircular, all while the delivery tip is travelling an up-down path asthe delivery tip circumscribes the circular component path about thecircumference of the mold cavity.

Where the mold cavity has relatively greater dimensions between theinner and outer walls, or where the mold cavity has narrower and broaderpassages about the perimeter of the mold cavity, or where more than oneinner wall 36 extends through the mold cavity, the delivery tip movesalong a transverse component of the path which from time-to-time,extends with a radial component as well as a circumferential component,in order to deliver a relatively consistent density and distribution offiber and resin to all areas of the mid-height level of the mold.

FIG. 12 also suggests the fluffy nature of the fiber exiting wand 78, asa length of fiber fluff 104 extending from the top of the mold. It willbe understood that the air passing through jet head 76 to fluff anddrive the fiber, exits the delivery system assembly at the exit end ofwand 78. Accordingly, a certain volume of air enters the mold with thefiber. That air volume exits the mold both through the top of the moldand through mold steam release ports 35 in the mold side walls andbottom wall. While the movement of the air fluffs the fiber and drivesthe fiber into the mold, that air is typically turbulent whereby thefiber entering the mold through wand 78 has turbulent movementcharacteristics, such that the fiber moves in somewhat-controlled, butrandom, directions. Accordingly, the PLC is programmed to deliver thefiber-resin combination, in the first phase, close to the bottom of themold, whereby the movement of the fiber is somewhat controlled by directcontact with the bottom wall of the mold. In the second phase, the fiberis delivered close to the top of the fiber which was delivered in thefirst phase, whereby movement of the fiber being delivered in the secondphase is somewhat controlled by direct contact with the fiber which wasdelivered in the first-phase of the mold filling.

The movement of the delivery tip illustrated in FIG. 13 illustrates themovement of the delivery tip during a third phase of delivery of fiberand resin into the mold. The movement illustrated in FIG. 13 iscommenced after completion of the movement contemplated in FIG. 12 inthe mid-height portion of the mold. In the movement illustrated in FIGS.13, the delivery tip extends to a location near the top of thetop-to-bottom height of the mold. Up-down arrow 100 again indicates thatdelivery tip 84 moves vertically up and down in the mold. In this thirdphase of delivery of fiber and resin into the mold, such up and downmovement is confined to an upper portion of the mold, such as to theupper ⅓ of the height of the mold. The difference in height of thedelivery tip can be seen conceptually by comparing the length of sleeve82 which is visible in FIG. 13 to the length of sleeve 82 which isvisible in FIG. 12. Given that the same sleeve is being used in both ofFIGS. 12 and 13, given that a greater portion of the length of thesleeve is visible in FIG. 13, the delivery tip is at a higher elevationin the mold in FIG. 13 than in FIG. 12.

Again, curvilinear arrow 102 indicates that, as delivery tip 84 ismoving in such up-down motion in this third phase of delivering fiberand resin to the mold, the delivery tip is also moving transverselyabout the horizontally-defined profile of the mold volume, thusthree-dimensional motion about the circumferential outline of the moldcavity between inner and outer walls 36, 38. The actual definition ofthe transverse component of the path depends on the profile of thecavity between walls 36, 38. Where the mold cavity is relatively narrowand circular as in the mold illustrated in FIG. 3, the transversecomponent of the path travelled by delivery tip 84 may be generallycircular, all while the delivery tip is travelling an up-down path asthe tip circumscribes the circular component of the path about thecircumference of the mold cavity.

Where, by contrast, the mold cavity has relatively greater dimensionsbetween the inner and outer walls, or where the mold cavity has narrowerand broader passages about the perimeter of the mold cavity, or wheremore than one inner wall 36 extends through the mold cavity, thedelivery tip moves along a transverse portion of the path which, fromtime-to-time, extends with a radial component, as well ascircumferential component, in order to deliver a relatively consistentdensity of fiber and resin to all areas of the upper portion of the moldcavity.

FIG. 13 further suggests the fluffy nature of the fiber exiting wand 78,as multiple lengths of fiber fluff 104 extend from the top of the mold.

FIG. 14 shows both molds after the desired quantity of fiber and resinhave been placed in the molds and caps 106 have been placed in the topportions of the molds. Fiber fluff 104 is seen extending from the topsof the filled molds. FIG. 14 also shows that steam release ports extendthrough both the sidewalls and caps of the molds. In addition, steamrelease ports extend through the bottom walls of the mold base plates 40under the mold cavities.

While three levels, elevations of movement of the delivery tip, in threephases of delivering fiber and resin into the mold cavity, have beenillustrated, fewer than three levels of movement, or more than threelevels of movement are contemplated. The number of levels of movement isdriven at least in part by the overall height “H” of the mold, and mayalso be driven by the level of precision needed in the consistency ofdensity and distribution of the fiber and resin throughout the insertcores.

A significant benefit of the invention is that the relatively smallcross-section of the delivery tip allows the insertion of the deliverytip into portions of the mold cavity which have rather limitedcross-sections. In the illustrated embodiments, wand 78 may have amaximum cross-section outer dimension of e.g. about 0.5 inch to about0.75 inch. And resin conduit 70 is even smaller in cross-section.Accordingly, and given the precision of transverse placement of deliverytip 84 relative to the underlying mold cavity which is available usingposition sensors for positioning both the mold and the wand, thedelivery tip can be inserted into the mold cavity between inner andouter walls 36, 38 which are no more than 1 inch apart or less. Giventhat jet head 76 delivers the fiberglass roving to the delivery tip as afluffed fibrous product, the cross-section dimension/diameter of thefluffed product after it exits wand 78 can be substantially greater thanthe outer diameter of the wand. Thus, a wand having an outer diameter atthe delivery tip of 0.5 inch, and an inside diameter of e.g. 0.42 inch,can deliver a fluffed fiber product having a cross-section nominallyequivalent to a diameter of 0.5 inch or more.

Once the user determines the general cross-section of the fluffed fiberleaving the delivery tip, the user can determine the desired transversepositions, movement, of the delivery tip along the delivery tip path inorder to provide a substantially uniformly-distributed packing of thefiber and resin combination in the insert core being fabricated in themold.

As suggested above, in the process of delivering fiber to the moldcavity, the delivery tip performs a continuous transverse andup-and-down motion, thus traversing a zigzag path wherein the deliverytip travels transversely during each up and/or down movement.

As a result, the fiber is deposited in the mold cavity as afluffed/expanded rope/roving in a pattern which leaves a wave-like,undulating appearance in the finished product, as illustrated in FIG.15, the wave-like appearance, as at 116, optionally including a patternwhich reflects turbulence in the formation and/or appearance of thepattern. However, as also seen in FIG. 15, since the fiber issimultaneously experiencing the turbulent movement of air through andout of wand 78, the fluffed fiber does deviate from the predominantwave-like pattern.

Thus, a visual representation of the product, once removed from the moldafter curing, shows a combination of the wave-like elements as well asmore-circular 118 and other non-wave-like, non-undulating, but stillcurvilinear, components of the fiberglass strands/fibers/fluffed roving.

PLC 90 can, in the alternative, be programmed to perform its transversemovements and its vertical movements independently such that thetransverse movements and the vertical movements are executed independentof each other in time. Further, the magnitudes of the vertical componentrelative to the transverse component can be modified such that one ofsuch components is more dominant than the other. Where the vertical,up-down component becomes more dominant, the wave-like pattern becomesmore columnar, namely the height/width ratio of the waves is greater.Where the transverse component becomes more dominant, the height of thewave-like pattern decreases and the pattern becomes relatively flatterin appearance.

The invention can be used to fill mold cavities which contain multipleexhaust gas-carrying pipes because the PLC can be programmed at willregarding the predetermined path; and the user can pre-determine thedesired path.

The invention can be used to fill mold cavities where there is apartial-height barrier between cavity portions. Wand 78 is e.g. 0.5 inchoutside diameter, 0.42 inch inside diameter. A larger outside diameterlimits the ability to insert the delivery tip into small spaces in themold cavity, thus limits the ability to provide consistent density anddistribution of the fiber. Smaller outside diameter interferes with theability of the wand to provide appropriate fluffing to the fiber roving.Because of the relatively small outside diameters of the exit end ofwand 78 and delivery tip 84, and the versatility to program the PLCregarding transverse movement of the delivery tip, the system of theinvention can be used to fill mold cavities which have severecross-section variations between cavity portions, deliveringproportionately consistent density and distribution of the fiber-resinmixture to both more restricted cross-section portions, and lessrestricted cross-section portions, of the mold cavity.

Once the mold has been filled and cap 106 has been put on the mold, themold is passed through a curing oven 110, where the binder is heated tocure the binder, which sets, and thereby establishes, a fixed shape ofthe resultant fiberglass-binder mixture.

The setting/curing of the binder stabilizes the collectiveconfigurations of the fiberglass strands in the wave-like, undulatingconfigurations created in mold cavity 42, such that the resultingmuffler insert core is shape-constant, shape-stable, though somewhatdeformable, whereby the resulting cured/set fiberglass-binder core 108can be manually handled without necessarily jeopardizing theshape/configuration of the cured product. R is this stabilizing of thefiberglass product, in combination with uniform distribution of thefiberglass in the product, which is critical to being able to ensurethat the fiberglass fills substantially the entirety of the cavity inthe muffler when the binder burns off under the influence of exhaustgases from the vehicle engine.

After curing the binder by exposing the molds to the e.g. 600 degrees F.heat in the oven, the so heated molds are allowed to cool to workingtemperature such that the molds can be handled safely without risk of aworker being burned. The resultant insert core is then removed from themold at a de-mold station 112 and forms the core of the finished mufflerinsert.

The resulting shape-constant insert core product may have residualfiberglass strands extending from e.g. the top of the core, the top ofthe core being defined consistent with the top of the mold. Once thecured core 108 has been removed from the mold, any such excessfiberglass material, now stiffened by the cured binder, can be removedusing a cut-off saw. The cut-off process can also be used to trim theproduct to the specified length, if necessary.

Once the excess material has been cut off, including conforming theproduct to the specified length, the resulting cured fiberglass-binderproduct core 108 generally represents the size, shape, and the overallconfiguration of the fiberglass-based insert product which is desired,for insertion into a cavity inside a muffler shell.

Whatever the nature and/or structure of the cured, shape-constant core,the next stage in fabrication of the insert is to shrink wrap the corein plastic film at a shrink-wrap station 114 to create the finishedmuffler insert. A wide variety of single and multiple layer shrink filmsare suitable for such shrink wrapping. The intended function of theshrink film is generally to temporarily package the core until theinsert is assembled into a muffler shell. Thus, the finished insert issubjected to only limited handling before the role of the shrink filmhas been completely satisfied. Accordingly, the shrink film can beselected from films which have limited abuse tolerances, which generallyapplies to films which are relatively lower in cost.

In general a polyethylene shrink film, one mil thick, is suitable foruse as the shrink wrapping film.

In the resultant product, the shrunk plastic film overlies thefiberglass-binder core, providing a plastic-wrapped insert which fitsclosely inside the inner dimensions of the shell of the muffler, andclosely about/outside of any tubes inside the outer shell of themuffler.

The resulting shrink-wrapped product is generally rigid, though somewhatpliable, deformable, and so is able to be conformed to slightirregularities in the inlet exhaust pipe coming from the engine, orslight irregularities in the inner surface of the outer shell of themuffler. The plastic film surrounds the outer circumference of thecontained fiber-binder core and generally wraps around the ends of thecore, so as to present generally smooth plastic surfaces to the innersurface of the muffler shell, as well as to any end plates or transitionportions of the muffler shell.

When the insert, as part of the fully-assembled muffler, is initiallyexposed to the hot exhaust gases of a vehicle engine for an extendedlength of time, such as an hour or so, the plastic shrink film burnsoff. The binder burns off at sustained temperatures of e.g. at least 600degrees F. The rate and temperature of binder burn-off varies withselections of different binders. In any event, both the plastic and thebinder will ultimately burn off. Once the binder and plastic film haveburned off, all that remains is the continuous-length fiberglassstrands.

The process by which the insert has been fabricated, and loaded into themuffler, in the invention, results in superior uniformity of density anddistribution in the fiberglass which remains inside the muffler shellafter the binder and plastic have burned off. Such uniformity of densityand distribution contributes to efficient sound attenuation as well asto uniformity of temperature distribution inside the muffler and aboutthe muffler shell.

Those skilled in the art will now see that certain modifications can bemade to the apparatus and methods herein disclosed with respect to theillustrated embodiments, without departing from the spirit of theinstant invention. And while the invention has been described above withrespect to the preferred embodiments, it will be understood that theinvention is adapted to numerous rearrangements, modifications, andalterations, and all such arrangements, modifications, and alterationsare intended to be within the scope of the appended claims.

To the extent the following claims use means plus function language, itis not meant to include there, or in the instant specification, anythingnot structurally equivalent to what is shown in the embodimentsdisclosed in the specification.

1. A molded fiberglass-based sound attenuating muffler insert corecomprising a generally shape-constant cured mixture of continuousfiberglass roving and cured liquid resin binder, said insert core havingan outer surface configured to interface with an inside surface of amuffler shell into which said insert core is adapted to be assembled soas to provide fiberglass-based sound attenuation in such muffler whensuch muffler is fully assembled, whereby such muffler insert core isadapted to maintaining a relatively constant shape configured tointerface with such inside surface of such muffler shell, wherein saidcontinuous fiberglass roving has been fluffed so as to reduce a densityof such roving, and wherein said fluffed roving, in elevation view, ofsaid insert core, exhibits a conspicuously wave-like, undulatingpattern.
 2. A muffler insert core as in claim 1 wherein portions of saidfluffed roving deviate from the wave-like undulating pattern.
 3. Amuffler insert core as in claim 1 wherein portions of said fluffedroving randomly deviate from the wave-like undulating pattern.
 4. Amuffler insert core as in claim 2 wherein portions of said fluffedroving exhibit generally isolated circular patterns.
 5. A muffler insertcore as in claim 1, said insert core having been fabricated by insertingan exit wand tip of a jet head into a core mold, and moving said exitwand tip along an up and down zigzag path while delivering the fluffedfiberglass roving into the mold. 6-28. (canceled)
 29. A muffler insertcore as in claim 4 wherein the circular patterns of said constrainedfiberglass roving are generally isolated from one another.
 30. A mufflerinsert core as in claim 1 wherein said fluffed fiberglass roving in saidinsert core comprises continuous-length fluffed fiberglass roving. 31.Use of a molded fiberglass-based sound attenuating muffler insert in avehicle muffler wherein the muffler insert comprises a combination offiberglass roving and cured liquid resin binder, the muffler inserthaving an outer surface configured to interface with an inside surfaceof a shell of the muffler, the muffler insert being adapted to maintaina relatively constant shape while being inserted into the muffler shell,and being configured to interface with the inside surface of the mufflershell, and wherein the fiberglass roving has been fluffed so as toreduce a density of such fiberglass roving and wherein the fluffedroving, constrained by the cured liquid resin binder, in elevation viewof the insert, prior to the insert being inserted into the mufflershell, exhibiting undulating, and other curvilinear, patterns, andwherein the cured liquid resin binder is susceptible to being burned offby heat of engine exhaust gases passing through the muffler whereby theburning off of the cured liquid resin binder releases the constraint ofthe resin binder on the fiberglass after the insert has been placedinside the muffler shell and exposed to the engine exhaust gases. 32.Use of a molded fiberglass-based sound attenuating muffler insert as inclaim 31 wherein the fiberglass roving is a continuous-length fiberglassroving in the muffler insert.
 33. Use of a molded fiberglass-based soundattenuating muffler insert as in claim 31 wherein portions of thefluffed constrained fiberglass roving deviates from such undulatingpatterns.
 34. Use of a molded fiberglass-based sound attenuating mufflerinsert as in claim 31 wherein portions of the fluffed constrainedfiberglass roving deviates randomly from such undulating patterns. 35.Use of a muffler insert core as in claim 31 wherein portions of thefluffed constrained fiberglass roving exhibit generally circularpatterns.
 36. Use of a muffler inset core as in claim 31 wherein thecircular patterns of the constrained fiberglass roving are generallyisolated from one another.
 37. Use of a muffler insert core as in claim31, the insert core having been fabricated by inserting an exit want tipof a jet head into a core mold and moving the exit want tip along an upand down zigzag path while delivering the fluffed fiberglass roving andresin into the mold.
 38. Use of a muffler insert core as in claim 31wherein the fluffed fiberglass roving in the insert core comprisescontinuous-length fluffed fiberglass roving.